Growth Conditions for ''Arabidopsis thaliana''

Temperature

Grow chamber temperatures are kept as close to 22°C as possible.

Note: The shelves used to grow gnotobiotic Arabidopsis thaliana plants are enclosed by a mylar and fabric cover that helps to insulate against changes in temperature, and to raise the internal temperature slightly above the 18°C temperature of the grow room.

Arabidopsis thaliana plants grown in non-sterile environments will be in the greenhouse, which has an internal temperature that is slightly higher and more stable than that of the surrounding external atmosphere. Although there will be more temperature fluctuation in this location, the plants will be exposed to identical conditions when they are transferred outdoors.

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Lighting

Lighting should be around 100-200 umol/m2/s during the 16 hour photoperiod.

Note: Our grow chamber is equipped with sets of 4 flourescent bulbs per shelf - each bulb is 2650 Lumen, and so 4 of them in conjunction equals 10600 lumen. Based on the size of our shelves, that is roughly equivalent to 10600 lux (as each of our shelves are around 1 square meter). A conversion website [1] shows that 100-200 umol/m2/s is equivalent to 7,400 and 14,800 lux, respectively. Thus, our approx. 10,600 Lux light source falls within the necessary range of lighting.

Note: After recognizing that many of the lights mentioned above were defective (owing to the fact that the fixtures themselves were purchased in 1994), we purchased 6 new fluorescent grow lights that would be smaller and more efficient. These lights are 6500K and feature a 5,000 Lumen output. As stated above, lumens are approximately equivalent to lux in this experiment given that our shelves are around 1 square meter. Given that 3 of these lights would add to approximately 15,000 Lux, we would only slightly overshoot the 14,800 lux bar that corresponds to 200 umol/m2/s. [2]

Lighting levels and the photoperiod in the greenhouse is based on whatever light comes in through the windows from the outside.

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Irrigation

Irrigation is only needed for Arabidopsis thaliana plants grown in non-sterile conditions. Once seed flats have been transferred to the greenhouse, keep soil well watered until true leaves have appeared on seedlings - at this point, "reduce the watering frequency to as low as once or twice per week as needed" [3]. Watering can be conducted by misting the plants for 30 seconds with a hose mister.